The news is full of stories about the "new trend" of urban gardening and now people who have jumped on the bandwagon are now crying foul that they haven't got back what they spent. I never expected to get back what I put in the first year or two but once the beds are established, I should get plenty back.
Even this year, we did pretty well despite having lousy dirt (not soil, just dirt) and not really knowing how the light would (or wouldn't) fall in our yard.
two cucumber seedlings produced about 25 cucumbers
two zucchini seedlings produced about 15 large zucchini
two bags of onion sets are still producing, pretty much 90% success rate
radish seed tape produced plenty of radishes -- almost too many to eat.
carrot seed tape produced lots of carrots but too close together
potatoes each produced at least a pound of potatoes in return -- we easily got 12 lbs of potatoes
eight scarlet runner bean seeds produced many pounds of beans plus attracted hummingbirds to the yard.
Jury is out:
two eggplant seedlings produced only one eggplant but a lot of amusement and pretty flowers
a dozen strawberry plants produced few berries (two pints?) but those it did produce were ridiculously tasty
four summer squash plants from seed (we planted more but only 4 sprouted) produced about 12 small squash plus several that rotted or were eaten by slugs, etc.
a half-dozen peas planted from seed produced about 4 pods each -- not much but enough for lunchbox snacks
lettuce -- seed tape produced closely grown plants that were great for a while then all wilted at once.
six pumpkin seeds produced two plants which yielded three pumpkins, one of which rotted on the vine. However, they are pretty and will be useful for Halloween.
tomatoes -- lots of seedlings, some purchased, some given to us -- produced almost no ripe fruit.
edamame -- 6 seedlings produced some beans but not enough to make a side dish for the three of us plus I mistakenly left them on the plants too long and they dried there.
spinach -- I planted it too late and what grew just bolted.
peppers -- killed by the heat of the greenhouse because we didn't un-pot them and plant them in the garden.
For most of the summer, we haven't had to buy too many vegetables, just supplemental. I figure we got about $100-$125 in vegetables out of the garden after spending about $70 on seeds and seedlings (I'm not counting what we spent on dirt or materials for the raised beds). Not a fantastic return, admittedly, but the seeds we bought will last us through one or two more seasons, to be supplemented by a few seedlings. We have also tried saving a few seeds to plant next year.
The biggest value of course is not the actual cost of the food but knowing where it comes from and having the freshest possible food available.